The detection of concentrations of oxygen, carbon monoxide, carbon dioxide or other constituents or contaminants in ambient air has become ever more important in the pursuit of clean, healthy air. It is particularly difficult to obtain accurate readings in environments where the concentrations of different species are rapidly changing. Diode lasers have been used to measure atmospheric species. In diode laser systems a laser beam is directed through a sample volume or cell containing a gas or gasses each of which absorb laser energy at specified wavelengths. The type of gas in the cell can be determined by noting the wavelength of the energy absorbed or by supplying the cell with a known wavelength which corresponds to the absorption wavelength of a particular gaseous species of interest. The concentration of the gas can be computed from the pressure, the temperature, and the amount of absorption, which may be accomplished by comparing the amount of incident radiation to the amount of transmitted radiation: the greater the absorption, the greater the species concentration. To achieve the absorption in these systems a long optical path is typically required, which is generally accomplished by providing a cell or sample volume with a substantial height using multiple passes of light. In order to draw the atmospheric species into the cell, typically a pump is used. The pump is bulky and requires a substantial amount of power. Therefore these systems are not suitable for applications which require low profile and portable devices. More importantly, the pump causes a large pressure drop when activated. This pressure drop causes the density of the atmospheric species introduced to the cell to change, thereby resulting in an altered sample different than the ambient conditions being monitored. Accordingly, inaccurate readings of species concentration in ambient air are obtained. In addition, the pump, which is interconnected with the sample volume by a port that is usually smaller than the cross-sectional area of the sample volume, causes turbulence and recirculation of gases in the cell or sample volume which also affects the species concentration of the sample and the accuracy of species concentration measurement of the ambient air. Moreover, the height of the cell can limit the response time, which can deleteriously affect accuracy when dealing with changing ambient conditions. The pumping time to replace the gas in such a sample volume is typically long, taking several seconds to refresh the gas sample.